Buildings on the Fred Finch Youth Center campus are seen in Oakland, Calif. on Friday, Nov. 30, 2012. Authorities are searching for suspects believed to have severely beaten a 16-year-old autistic girl who walked away from the facility Tuesday night.

Photo: Paul Chinn, The Chronicle

Buildings on the Fred Finch Youth Center campus are seen in...

Image 2 of 3

Women walk on the grounds of the Fred Finch Youth Center in Oakland. Federal law requires care homes' doors to be unlocked.

Photo: Paul Chinn, The Chronicle

Women walk on the grounds of the Fred Finch Youth Center in...

Image 3 of 3

A building on the Fred Finch Youth Center campus is seen in Oakland, Calif. on Friday, Nov. 30, 2012. Authorities are searching for suspects believed to have severely beaten a 16-year-old autistic girl who walked away from the facility Tuesday night.

State officials have joined an investigation into the events leading up to an attack on an autistic 16-year-old girl who walked away from a care home for developmentally disabled youths in Oakland, lost the staff members who were following her and was found assaulted on a bus in San Francisco two days later.

The girl, who has the mental capacity of a 9- to 12-year-old, left the state-licensed Fred Finch Youth Center at 3800 Coolidge Ave. at 7 p.m. Tuesday, Oakland police said Friday. The center specializes in emotionally disturbed and developmentally disabled youths and does not lock its doors, in accordance with federal law.

A Muni driver found her disoriented on a bus at 8 p.m. Thursday, officials said. She was being treated Friday at Highland Hospital in Oakland. Details on her condition were unavailable.

No arrests have been made, and although Oakland police said the girl had been a victim of a crime, they released few details.

"We're investigating the circumstances of her disappearance," said Sgt. Chris Bolton, a police spokesman. "For that reason, we are not commenting on any specific offenses." The Chronicle is not naming the victim because she is a minor.

The girl's parents placed her in the 14-bed Fred Finch center six months ago, officials there said.

Headed to BART

The center's CEO, Tom Alexander, said the girl left Tuesday night despite efforts by staffers to persuade her to stay. "We did all that we could to counsel the youngster to return to the agency," he said.

Two staff members "shadowed" her on foot and in a car for about 2 miles, until she reached the Fruitvale BART Station, Alexander said.

BART police stopped the staff members in the car, however, just as they were trying to get a closer look by driving near the platform. The staffers "identified themselves and explained the circumstances - in that very brief time frame, she disappeared," Alexander said.

BART officers contacted Oakland police while the staffers searched the area, to no avail. The Fred Finch center did not file an official missing person report with Oakland police until after midnight.

Centers for developmentally disabled children are overseen by the state Department of Social Services. A spokesman for the agency, Michael Weston, said officials there were investigating the girl's disappearance.

Unlocked doors

Weston stressed, however, that federal law requires licensed care homes to keep their doors unlocked and prevents them from restraining residents, even children, from leaving.

"If a child was to leave," Weston said, "staff is to redirect them to stay, but they don't have the authority to block them or physically restrain them."

Weston said staff members are instructed to follow any youth who leaves unsupervised and then contact police if they appear to be in danger.

The Fred Finch Youth Center was founded in 1891 as an orphanage. It now has homes in several Bay Area locations as well as in San Diego County.

In a statement, the center stressed that "participants may come and go at will."

"We believe that no young person should be hurt as a consequence of an impulsive act," the center said. "With our community, we are deeply upset by this youngster being assaulted while she was on the run."